SHS-produced Ni-Co-Al-Mg-O catalysts for dry reforming of methane

Oxide catalysts Ni-Co-Al-Mg-O, Ni-Al-Mg-O, Co-Al-O, and Co-Mg-O have been prepared by combustion synthesis and characterized by XRD, Fourier transform IR spectroscopy (FTIR), SEM/EDS, TEM, and nitrogen porosimetry. Their catalytic activity in the process of dry (carbon dioxide) reforming of methane was studied by gas chromatography at different temperatures. Feed gas contained equal amounts of methane, carbon dioxide, and nitrogen and the effect of catalyst composition and temperature on the catalytic activity, selectivity, and product yields were recorded.     

Antioxidant and lipoxygenase inhibitory activities of pumpkin seed extracts

Pumpkin seeds have been implicated in providing health benefits. However their antioxidant or anti-inflammatory activity of their extracts has never been studied. Therefore, four commercially available pumpkin seeds were treated with two different extraction methodologies in order to obtain fractions with different content. The extracts were screened for their antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and for their inhibitory activity against lipid peroxidation catalyzed by soybean lipoxygenase.Most extracts tested have demonstrated radical scavenging activity, which depends on their total phenolic content, with fractions rich in phenolics showing the strongest activity. On the other hand, the phenolic content of extracts does not determine their activity against lipoxygenase, as acetone and polar lipid fractions are its strongest inhibitors. The presence of molecules being able to scavenge radicals and inhibit lipoxygenase in pumpkin seeds may in part explain the health benefits attributed to them.     

Influence of Preheating Temperature on Solution Combustion Synthesis of Ni–NiO Nanocomposites: Mathematical Model and Experiment

Solution combustion synthesis (SCS) is a widely recognized method to synthesize nanoscale materials. In this work, an attempt was made to analytically simulate (using the Semenov method) and evaluate the influence of preheating temperature on flame temperature as well as on physicochemical characteristics of SCS products. Preheating was found to affect combustion temperature only slightly. An increase in preheating temperature led to a decrease in the induction period due to enhanced heating rate and an increase in cooling time as a result of additional exothermic reactions taking place at higher temperatures. Variation in cooling time caused changes in composition and microstructure of product. For the first time, a mathematical model of SCS was suggested.     

Antioxidant and anti-inflammatory activity of red and white wine extracts

Two commercially available Greek wines were treated with two different extraction methods in order to obtain either the total lipid fraction or several fractions containing different classes of phenolic compounds.     

Hybrid TPS: A novel hybrid thermal protection system for atmospheric entry space probes based on SHS-Produced MgO/spinel refractories

A novel Hybrid Thermal Protection System (Hybrid TPS) for space probes entering planetary atmospheres at very high velocities has been designed and tested. The system mainly consists of a coarsely porous MgO/spinel refractory made by SHS and filled with a reinforced phenolic material creating a hybrid system. The two main constituents act synergistically protecting each other from the extreme heating developed during atmospheric entry and reduce the recession and irregularity at the front surface. The results of the investigation have shown that the hybrid system offers satisfactory protection at heat fluxes of more than 2000 kW/m₂ and total heat loads of more than 200 MJ/m₂ and is thus a promising material for high-speed atmospheric entry usages.     

The crossover of daily work engagement: Test of an actor–partner interdependence model.

This study of 62 dyads of employees (N = 124) examined the crossover of work engagement—a positive, fulfilling, work-related state of mind that is characterized by vigor, dedication, and absorption. We hypothesized that work engagement crosses over from an employee (the actor) to his or her colleague (the partner) on a daily basis. The frequency of daily communication was expected to moderate the crossover of daily work engagement, which in turn would relate to colleagues’ daily performance. Participants first filled in a general questionnaire and then completed a diary study over 5 consecutive workdays. The hypotheses were tested with multilevel analyses, using an actor–partner interdependence model. Results confirmed the crossover of daily work engagement, but only on days when employees within a dyad interacted more frequently than usual. Moreover, we found that actor’s work engagement (particularly vigor), when frequently communicated, had a positive indirect relationship with partner’s performance through partner’s work engagement. Finally, results showed that actor’s vigor was negatively related to partner’s performance when communication was low. However, this negative effect was counteracted when mediated by the vigor of the partner. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oxidative Dehyrodimerization of Methane Using Manganese‐based Catalysts Made by Self‐propagating High‐temperature Combustion Synthesis

The self‐propagating high‐temperature synthesis (SHS) method has been used to produce a range of active manganese‐based catalysts for the oxidative dehydrodimerization of methane. Catalytic activity was measured at temperatures between 920 and 1120 K under a range of conditions. In the best case found, the ethylene yield reached about 26 % with a selectivity of 85 % and a methane conversion of 30.2 %. Some ethane, propylene, propane and hydrogen were also obtained. The addition of alkaline elements, promoted by halides, increased the yield of ethylene at the expense of reduced stability. The catalytic activity was found to be enhanced by careful control of SHS conditions and various post‐synthesis treatments of the materials.     

Job resources boost work engagement, particularly when job demands are high.

This study of 805 Finnish teachers working in elementary, secondary, and vocational schools tested 2 interaction hypotheses. On the basis of the job demands-resources model, the authors predicted that job resources act as buffers and diminish the negative relationship between pupil misbehavior and work engagement. In addition, using conservation of resources theory, the authors hypothesized that job resources particularly influence work engagement when teachers are confronted with high levels of pupil misconduct. In line with these hypotheses, moderated structural equation modeling analyses resulted in 14 out of 18 possible 2-way interaction effects. In particular, supervisor support, innovativeness, appreciation, and organizational climate were important job resources that helped teachers cope with demanding interactions with students. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working in the sky: A diary study on work engagement among flight attendants.

This study aims to gain insight in the motivational process of the Job Demands-Resources (JD-R) model by examining whether daily fluctuations in colleague support (i.e., a typical job resource) predict day-levels of job performance through self-efficacy and work engagement. Forty-four flight attendants filled in a questionnaire and a diary booklet before and after consecutive flights to three intercontinental destinations. Results of multilevel analyses revealed that colleague support had unique positive effects on self-efficacy and work engagement. Self-efficacy did not mediate the relationship between support and engagement, but work engagement mediated the relationship between self-efficacy and (in-role and extra-role) performance. In addition, colleague support had an indirect effect on in-role performance through work engagement. These findings shed light on the motivational process as outlined in the JD-R model, and suggest that colleague support is an important job resource for flight attendants helping them reach their work-related goals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)